refactor(street-level): remove the remaining duplicated code and fakes

A duplicate scan of every module the PR adds (repeated 4-line blocks,
normalised) after gekh's dedup round left these:

- glyphs.js: the cone, ring and position glyphs share cachedGlyph(), wedge(),
  ring() and dot(). Checked with a recording canvas: all 20 draw calls keep
  the same path and fill/stroke state, so the glyphs are pixel-identical.
- panelPositionControls.js: one placeAt() for the three places that pin a
  panel's top-left corner as a fixed window.
- tiles.js: one warn() for the three background-failure logs.
- Tests: src/testSupport/streetLevelFakes.mjs holds the provider snapshot
  (uiState + presentation tests), the stand-in provider (core + controls
  tests) and one real-ray pinhole camera (view + coverage tests, which had
  each written their own). The coverage line-of-sight test still fails when
  refresh() stops passing its focus.
- qa-street-level.mjs: one waitForCoverage() for the five copies of the
  "on, drawn, settled, not key-gated" wait.

No behaviour change: unit 5862 pass, fixture gate 16/16, panel gate 5/5.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/ui/panelPositionControls.js

@@ -72,6 +72,14 @@ function fitWindowExtent(value, minimum, viewportExtent) {
  * Only a mouse or pen lifts and resizes a portable panel. On a phone the
  * rail is a scroll container, so a finger on a header is a swipe.
  */
+/** Pin a panel's top-left corner at (left, top) as a fixed window would sit. */
+function placeAt(panelEl, left, top) {
+  panelEl.style.left = `${left}px`;
+  panelEl.style.top = `${top}px`;
+  panelEl.style.right = 'auto';
+  panelEl.style.bottom = 'auto';
+}
+
 function isPrecisePointer(event) {
   const pointerType = event.pointerType || 'mouse';
   return pointerType === 'mouse' || pointerType === 'pen';
@@ -433,10 +441,7 @@ export class PanelPositionControls {
             Math.round(pos.top),
             panelEl,
           );
-      panelEl.style.left = `${left}px`;
-      panelEl.style.top = `${top}px`;
-      panelEl.style.right = 'auto';
-      panelEl.style.bottom = 'auto';
+      placeAt(panelEl, left, top);
       if (panelId === 'pp-toggles') {
         this._pinPanelToRight(panelEl);
       }
@@ -513,10 +518,7 @@ export class PanelPositionControls {
    */
   _liftPanelOut(panelId, panelEl, rect = panelEl.getBoundingClientRect()) {
     if (panelEl.classList.contains('panel-floating')) return false;
-    panelEl.style.left = `${Math.round(rect.left)}px`;
-    panelEl.style.top = `${Math.round(rect.top)}px`;
-    panelEl.style.right = 'auto';
-    panelEl.style.bottom = 'auto';
+    placeAt(panelEl, Math.round(rect.left), Math.round(rect.top));
     if (!panelEl.classList.contains('collapsed')) {
       panelEl.style.width = `${Math.round(rect.width)}px`;
     }
@@ -580,10 +582,7 @@ export class PanelPositionControls {
       const offsetX = event.clientX - rect.left;
       const offsetY = event.clientY - rect.top;
 
-      panelEl.style.left = `${rect.left}px`;
-      panelEl.style.top = `${rect.top}px`;
-      panelEl.style.right = 'auto';
-      panelEl.style.bottom = 'auto';
+      placeAt(panelEl, rect.left, rect.top);
       panelEl.classList.add('panel-dragging');
       this._promotePanelZ(panelEl);